Method and apparatus for applying coating material to the inside of a container



P" 27, 1954 R. F. RUSSELL METHOD AND APPARATUS FOR APPLYING comma MATERIAL T0 THE INSIDE OF A CONTAINER Filed Dec. 29, 1949 1a Sheets-Sheet 1 FIG.

R ICHAR D F. RUSS ELL I v INVENTOR.

April 2 1954 R. F. RUSSELL METHOD AND APPARATUS FOR APPLYING COATING MATERIAL TO THE INSIDE OF A CONTAINER Filed Dec. 29, 1949 13 Sheets-Sheet 2 Q In I h 8 K) I L) H Q) r a g d p G (1 L L q A A (F RICHARD F RUSSELL mmvroza.

BY g g #464.

FIG. 2

April 27, 1954 R F RUSSELL 2,676,895

MATERIAL TO THE INSIDE OF A CONTAINER 13 Sheets-Sheet 3 FIG. 3

RICHARD F. RUSSELL INVENTOR.

April 27; 1954 R F USSELL 2,676,895

. R METHOD AND APPARATUS FOR APPLYING COATING MATERIAL TO THE INSIDE OF A CONTAINER Filed Dec. 29, 1949 13 Sheets-Sheet 4 FIG. 4

RICHARD F. RUSSELL JNVENTOR.

April 27, 1954 ussg 2,676,895

METHOD AND APPARATUS FOR APPLYING COATING MATERIAL TO THE INSIDE OF A CONTAINER 15 Sheets-Sheet 5 Filed Dec, 29, 1949 FIG. 7 I

RICHARD F. RUSSELL IN V EN TOR.

April 27, 1954 R RUSSELL 2,676,895

METHOD AND APPARATUS FOR APPLYING COATING MATERIAL TO THE INSIDE OF A CONTAINER Filed Dec. 29, 1949 13 Sheets-Sheet 6 RICHARD F. RUSSELL INVENTOR.

April 27, 1954 R. F. RUSSELL 2,676,895

METHOD AND APPARATUS FOR APPLYING COATING MATERIAL TO THE INSIDE OF A CONTAINER Filed Dec. 29, 1949 15 Sheets-Sheet '7 1'! 1a A II l H I 1 i \1 73 l l 70 .l- I HIM LP 1} [IE I m 67 @3 I04 75 6 hi 2 j I RICHARD F. RUSSELL FIG; ll INVENTOR.

Aprl] 27, 1954 RUSSELL 2,676,895

METHOD AND APPARATUS FOR APPLYING COATING MATERIAL TO THE INSIDE OF A CONTAINER Filed Dec. 29, 1949 13 Sheets-Sheet RICHARD F. RUSS ELL INVENTOR.

BY U FIG. 9A fl a K474 P" 27, 9 R. F. RUSSELk.

METHOD AND APPARATUS-FOR AP LYING COATING MATERIAL TO THE INSIDE OF- A CONTAINER 13 Sheets-Sheet 9 Filed Dec. 29, 1949 I IOO RICHARD F. R USSELL INVENTOR.

April 27, 1954 v R. F. RUSSELL 2,676,895

METHOD AND APPARATUS FOR APPLYING COATING MATERIAL TO THE INSIDE OF A CONTAINER Filed Dec. 29, 194$ 13 Sheets-Sheet 1O 1 PW i u 1a a I II I so |oa I oe 4- \Q; l l I no as I I r I00 :l u 9.9.. v \63 um 99 \l F u I02 m 9a I I RICHARD F-. RUQSELL IN VEN TOR.

April 27, 1954 Filed Dec. 29, 1949 METHOD AND APPARATUS FOR APPLYING COATING MATERIAL TO THE INSIDE OF A CONTAINER 13 SheetsSheet 11 91 v EL 96 i ii M ii J RICHARD F. RUSSELL INVENTOR.

FIG. r5

April 27, 1954 R. F. RUSSELL METHOD AND APPARATUS FOR APPLYING comma MATERIAL TO THE INSIDE OF A CONTAINER 15 Sheets-Sheet 12 Filed Dec. 29, 1949 Fl. I7

Fm. l6

RICHARD F. R USS ELL INVENTOR.

April 27, 1954 Filed Dec. 29, 1949 R.F.RUSSELL METHOD AND APPARATUS FOR APPLYING COATING MATERIAL TO THE INSIDE OF A CONTAINER 13 Sheets-Sheet 13 HVVENTUR.

Patented Apr. 27, 1954 METHODS AND APPARATUS: iron IAPPtYiNG .COATING: MATERIAL TO THE INSIDE or A CONTAINER Richardj F, Russell, :Ellmira N. Y., assignor to American- La France Foamite- Corporation, Elmira, N. 3L, a corporation of New York Application master 29, 1949, seems. 135,704

ZZClaiihs.

The present invention pertains to new 'and'us'eful improvements in methodf and apparatus 'for applying coating material to the inside of atontainer It relates more particularly to a method and an apparatus for applying a coating of protective material such as tin to the interior of metal containerssuch'as a fire'extingui'sher shell and at the same time, heat treating the metal container I t v Prior to the present invention, the usual practicefollowed in applying a protective coating of a material such as tin to theginterior of a'fire eX- tinguisher shell was to dipthe entire shell in a hot bath of molten tin by hand The thickness of the coating of tin on the inside of the shell obtained by such a hand dipping operation was difficult tocontrol and generally. exceeded the thickness required to give the protection desired. In the case of costly coating material's suchas tin, this increased the cost of the container considerably In addition, when the entire shell is dipped in hot tin, the exterior of the shell must he protected as by painting, in order to prevent the tin from adhering to the outside thereof, and this paint must then be removed from the exterior of the shell The present invention is directed to reducing' the cost of manufacture'of such containers. To accomplish this, it providesa method and appa ratus for applying coating material such as tin to the interior of a vessel or'cont'ainer without hand dipping and insuch a manner that a coating of the desired thickness is obtained This reduces the labor costs and results in a saving in the amount of coating material that is required to be used. In addition, the present invention provides for the reduction of losses due to wasteful drag out of coating material. Further, the present invention renders the painting of and the removal of paint from the outside of the containers prior to and after the dipping unnecessary. I v x v t "Jhe presentinvention also provides. for a heat treatment of metal containers as they are-being coated in order to relieve strains and to remove season cracks that may develop in containers made of certain metals due to hard working of the metal, such as seam welding, drawing, or

riveting V I The-present invention'may be usedfor spray coating the interior-of 'a container withany suitable material, either-metal or chemical, that is fluid or can be made fluid (-rnolten) in a temperature rang up to and including 1",000" F.

Examples of materials that are frequently-used for protective coatings and which may be used .in accordance with the present invention aretin,

cadmium, v. and zinc. I While in the embodiment of the invention described. and illustrated herein, specific'reference will be made to the coating of fire extinguisher shells, it will be understood that the invention can be readily adapted for use in coating the inside of any suitable container or vessel wherefa coating on the interior is desired or is an essential requirement.

Various other objects and.. advantages of the present invention will be apparent and will be best understood from the following description and the accompanying drawings in which:

Fig. 1 is a. side view of a machine embodying the invention;

Fig. 2 is a plan view of in Fig. 1; I

Fig. 3 is a section view taken along the line of Fig. 2; i

Fig. 4 is a section view taken along the line 4-42; of Fig.2;

Fig. 5 is a plan view of a carrier plate such as used in the machine shown in Fig. 1;

Fig. 6 is a fragmentary view in section along the line 'E-6 of Fig. 5;

the machine illustrated Fig; l is a section view taken along the line Fig. 8 is 'a fragmentary view in partial section taken in a vertical plane illustrating certain details of the heat treating chamber of the machine shown in Fig. 1; I ,7

Fig; 9 is a-plan view of a lower elevator assembly such as used in the machine shown inFig. 1

Fig. 9A is a fragmentary view in section taken along the line BA-9A of Fig. 9;

Fig. 10 is a side View of the lower elevator assembly illustrated in Fig. 9;

Fig. 11 is a section View Fig. 12 is a fragmentary view' in partial section taken in a vertical plane illustrating certain details of an upper elevator assembly such as used in the machine shown in Fig. 1;

Fig. 13 is a fragmentary plan viewillustrating certain details of the tin and flux trays and their connections to tin and flux tanks;

Fig. 14 is a side view taken from the right of the parts illustrated in Fig. 13;

taken along the line Fig. 15 isa side view taken from the left (if the Fig. .18 is aschematicwiring diagram for the aemsos 3 operating parts of the machine shown in Fig. 1; and

Fig. 19 is a schematic wiring diagram of a control circuit for the machine shown in Fig. 1.

As shown best in Figs. 1-4, there is a framework 20 at one side of which a reduction unit or gear box 2! is mounted (see Fig. 2). The reduction unit 2! is driven by an electric motor 22 and is connected through a flexible coupling 23 to a drive shaft 24. The drive shaft 2-4 extends transversely of the machine and is supported. in antifri'ction bearing pillow blocks 25 that are secured to the frame 20.

Intermediate the ends of the drive shaft 2%, a bull or drive gear 26 is mounted on and keyed to the drive shaft. As shown best in Fig. 4, the bull gear 26 meshes with and drives a secondary gear 21 that is mounted on and keyed to a con veyor drive shaft 28.

In addition to the conveyor drive shaft 28 there are three other conveyor shafts 29, so and ii that are located in spaced relation to each other around the frame 2Q. Each of the conveyor shafts extends transversely across the frame and may be rotatably mounted in bearings 32 that are secured to the frame 2%. Machined chain sprockets 33 are secured at both ends of each conveyor shaft and a link chain belt 34 extends around the sprockets 33 on the respective ends of each n of the conveyor shafts ZR-3i at the opposite sides of the frame 20.

Flight or carrier plates 35, on which the work is to be mounted, extend across the frame at and are secured at spaced intervals to links of the chain belts 34 by brackets 36. The chain belts 34 with the carrier plates 35 secured thereto thus form a continuous conveyor that travels horizontally in step by step movements over the table or work surface of the machine, then downward at the end of the machine and returns horizontally beneath the work area to the forward end, and then upward to the starting or loading point. A chain tightener may be provided for tightening the chain belts 34 or one of the conveyor shafts 28-3! may be adjustably mounted on the frame 20 as indicated at 37 (see Figs. 1 and 3).

The details of the carrier plates 35 are shown best in Figs. 57. As shown therein, the ends of the carrier plates 35 are equipped with equalizing flanged rollers 38 that run in a channel or track 39 secured to the frame Zil. Rollers it of the chain belts 34 ride on carrier angles that extend inwardly from the frame 2d. This arrangement provides a free running, self-aligning mechanism with all weight being carried by the frame 20.

The carrier plates 35 may be fabricated from stainless steel sheets and each plate forms a support for a row of rotatable work-carrying sleeves 42. The rotatable sleeves 42 are mounted on the carrier plates in plain and anti-friction bearings 43 and 44 and the lower ends of the workcarrying sleeves are provided with toothed rings 45 that are keyed to the sleeves. If necessary, the interior of the sleeve 42 may be lined with a ring of drawn aluminum or other suitable material held in position by the top or work holding ring on the sleeve 42 providing an air space between the sleeve and this inner ring to prevent heat transfer and the chilling of hot metal coating materials that may flow over the sleeves during the work cycle. A one-shot lubricating system, as indicated at 46 in Fig. 6, may be provided for supplying lubricants capable of withstanding high 4 temperatures to the rotatable sleeves 12 and the flanged rollers 38.

The upper ends of the sleeves 42 are provided with suitable means such as threads l'i, for securing a container 48 (indicated by the broken lines) in an inverted position on top of each of the rotatable sleeves 42 on the carrier plates 35. The containers d8 are secured to the sleeves on each carrier plate 35 as it reaches a loading station as indicated at 49. After the containers have passed through the work area and have been permitted to cool, they are removed from each carrier plate 35 as it reaches an unloading station as indicated at 50.

At the loading and unloading stations 39 and 59, a series of racks 5! are yieldably supported on bars 52 that are located beneath the carrier plates 35 at the loading and unloading stations. As a carrier plate reaches either the loading or t -eunloading stations 49 and 5%, the yieldably mounted racks 55 enter between each pair of the rotatable sleeves 42 and engage with the toothed rings 45 on lower ends of the sleeves to hold the sleeves against rotating while the carrier plates are being loaded and unloaded.

Upon leaving the loading station, the loaded carrier plate 35 with a container d3 supported in inverted position on each of its rotatable sleeves enters an enclosed chamber 53 that is suitably insulated to prevent heat loss. As seen best in Fig. 4, the chamber 53 has doors 5% and 55 that are automatically raised and lowered at proper times to permit the carrier plates and the containers supported thereon to enter and leave the chamber.

In the illustrated embodiment of the invention, the chamber 53 is divided into three zones to, 51 and 58. The first zone 56 is a preheating zone in which the temperature of the containers is raised to a temperature consistent wit. the work to be performed. When a coating such as tin is to be applied, this temperature will be in the neighborhood of 350 F. In the second or central zone 5?, a flux, if one is required, is applied at 180 to the inside of each of the containers supported on the carrier plate at a fluxing position of the conveyor while coating material at 575 F. is simultaneously applied to the inside of fiuxed containers supported on the carrier plate at the next position of the conveyor in this zone. The final zone 5%; is a heat treatment zone and it may be separated from the central zone by a door 53' that is also automatically raised and lowered at the proper time. In this zone, the containers with their insides having been coated are heated to the temperature of 600 and for the time required for heat treating the particular metal from which the container is made to relieve strains and season cracks such as result from the working of the metal from which the containers are made. In addition, any excess coating material is drained from the interior of the containers in this zone and is returned to its source to be used over again.

Electrical heating units 59, to, El and 62 of the resistance type may be employed to provide controlled heat in the preheating and heating zones of the chamber 53. However, other suitable means of obtaining controlled heat may be used for this purpose if desired. The heating units 59 and ti are fastened to bus bars and are suspended from the roof of the chamber 53 at points alon the side walls and between each row of containers in the preheating and heat treating zones, respectively. The heating units 60 and 62 are located beneath thevcarrierplates. and are-supported by thexfioorof thexchame draulic operated, double-actingcylinders :65. that are located on opposite sides of the frame 20.

The lower elevator 63- runson and is guided by four posts '65. 'As shown-best in Figs". 9-11, it includes a platform 61 on which-ea. tin tray 58 and a flux tray 69 aremounted... The flux tray 69 is preferably made of stainless steel and has an angularbottom draining to acentral return outlet it. tray 69, there is a conduit or manifold H that is supported in three equally spaced bearing support blocks E2. The manifold: H carries a series.

of upwardly extending spray pipes'lS that are fitted with spray nozzles 14.

The tin tray 68 may also be made of stainless steel and has an angular bottom draining to a central return-outlet 15. Centrally located in the tin tray there is a conduit or manifold '55 that is supportedin three bearing-blocks .11. Electric heating elements 18 of the resistance type are locatedbeneath the manifold 16 and aresecured to the under side of the bottom of the tin tray E8.-- The heaters '18 beneath the manifold are supported in the bearin blocks H. A series of upwardly extending spray pipes 19 with nozzles 89 at their ends which are capable of spraying the hot tin are spaced along the manifold it. The spray pipes 19 also have electrical heaters 19 surrounding them and these heaters are surrounded by protective sheathing 19a; to prevent shorting of the heaters;

The tin and flux trays 68 and 69- are assembled to the elevatorplatfo'rm- 61 and the' spray 'pipes folds so that each spray pipe Willbe-in reg- With One of the openings extendin through the'rotatable sleeves 4-2 in the carrier plates 35 that. are located at the flux'ing-and tinning positions'in the'centralzone'of the enclosed chamber This permits the spray pipes 13 and 19 to project through the sleeves and into'the interior' of the containers when the.:lower elevator is raised as shown in Fig. 4.

As shownbest in Fig. 1, thedoors, .54, 55 and 58' may be automatically raised and lowered at the proper times by connecting themto the lower elevator 63 by cables 8!,82 and 83,.respectively. The cables M, 82 and 83 run over pulleys that are supported on .an overhead frame 84." Thus, when the elevator is raised, the doors are lowered, and when the elevator is lowered, the doors are raised.

Nov/referring to Fig. 12,..each endof the upper elevator 65 is connected to a piston of a pneumatically or hydraulically operated, double-acting cylinder 85. The" cylinders 85 are secured to angles 86 that are supported on topof the framelii at opposite sides thereof. .Theupper elevator at carries an electric motor 81..that drives a line shaft 88 through a worm andwheel connection 5 88".. Secured at intervals along. thev line shaft 88 are .worms '89. that drive-Worm wheels st. The form wheels 9!! arelsecuredato ver-' tical shafts 8.1 that: aremounted on theelevator in anti-friction and plains-bearings and extend.

Centrally mounted in. the flux downwardly (see Fig. 12)., .The ,verticalshafts 9| each carry a driver 92 that-is urgedqto its downward position by a spring..93. The; drivers 93 are linedwith .a high temperature brake lining 95 and are positionedzdirectly above the tops of the row of containers-.48 on the carrier plate 35 that is located at the tinning position of the conveyor. As the lower elevator 63 is raised, the upper elevator 64 is lowered .until.the springbacked drivers 92 engage wlththe tops of the containers 48. The motor 81 then operates the drivers 82 to rotate the containers and the rotatable sleeves 42 at a desired speed as coating material is sprayed on the inside of the containers. This assures even distribution and complete coverage of the coating material over the inside surface of each of the containers.

Referring to Fig. 13, flux is delivered under pressure to the manifold H in the flux tray- 69 from a flux tank 95 by a centrifugal; pump 96 through a pipe 9'! and molten tin is delivered under pressure to the manifold '16 in th tin tray 68 from a tin tank 98 by a centrifugal pump 99 through a pipe I06. The return outlet 55 from the flux tray 69 is connected through a flexible pipe Edi to the flux tank 95 and the return outlet 15 of the tin tray 68 is connected through a return pipe I92 to the tin tank 98... The tin return pipe I62 makes a swiveled' connection at N33 to the return outlet 15 of the tin tray 68 and electrical heating elements I04 (see Fig. 11) of the resistance type are provided for heatin this connection and the tin return pipe: I02.

Universal connections are also provided for the pressure and discharge pipe leadingv from and returning to the storage tanks or the source from which the fluid fluxing and coating materials are pumped and the junctions of said pipes are positioned with relation to the movement of the lower elevator so that the ver-sine of the angle of action coincides and provides smooth action of the joint connections. All of the flexible pipes, manifolds, stand pipes and trays for handlin the molten coating material are electrically heated by means of electrical heaters of the resistancetype which are protectively sheathed to prevent shorting or grounding due to splatter of fluid metal.

The flux tank 95 and the 1 tin tank 98 are mounted at one side of the frame -25, as seen in Fig. 2, and they both may be of suitable-materials to resist corrosion. The flux tank 95 is provided with electric strip heaters 955 (see Fig. 16) that are automatically regulated by thermostats to maintain the fiux bath at a predetermined temperature which in the illustrated embodiment is in the neighborhood of F. The flux pump 95 has a self-contained motor at that drives a volute pump of a suitable size to provide a flushing action of the flux bath and the working por tions of the pump are preferably of Monel metal. The flux tank is also equipped with suitable strainers to prevent extraneous material from entering the line and is completely enclosed and insulated to prevent heat losses.

The tin tank 93 (see Fig. 17) not only serves as a storage reservoir for the molten tin, but also serves as a furnace for melting the tin ,or other coating material. It contains immersion electric heaters 156 that are of sufficient capacity.

to melt pig metal and at the same time maintain the constant temperature required to keep the metal in the tank in a molten-or fluid condition. The tin tank is heavily insulated to prevent :heat loss and is especially desi ned to serve as a melts 7 ing furnace to which metal in pig form may be fed directly and melted for use in the apparatus. It is equipped with an ingot feeding slide IE7 and screens for controlling dross. The tin pump 99 has a self-contained motor 99' that drives a volute pump of a suitable capacity for the pumping of the heavy fluid metal and its working portions may be of stainless steel.

The motor driven flux and tin pumps to and 99 are water cooled and each may be raised out of or lowered into its respective tank 95 or 98 by cables I58 (see Figs. 14 and 15). The water cooling systems have solenoid operated valves and the raising or lowering of the pumps 98 and d9 operates limit switches Hill and Hi respectively, that permit the pumps to be operated only when the pumps are lowered into pumping position in their respective tanks and also turn on the cooling water as soon as the pumps are lowered into their respective tanks.

The heat treatment zone 58, into which the containers pass after coating material has been applied to their inside surfaces, accommodates two or the carrier plates 35 with containers .3 supported thereon. However, the heat treatment zone may be made either longer or shorter, as desired so that the time and temperature of the heat treatment to which the containers are subjeoted will be as required.

The containers in the heat treatment zone 53 are supported in inverted position over a drain pan i I I that receives the excess coating material as it drains from the containers. The drain i i i is located immediately above the heating elements E2 on the floor of the heat treatment zone 58 (see Figs. at and 8.) and the excess coating material that is collected in the drain pan ii! is returned to the tin tank 98 by a drain pipe 32 that is heated by electrical heating elements I I3.

When the containers leave the heat treatment zone 55, they may be stopped at a cooling position of the conveyor, as indicated at 5 III, for one operation of the machine before proceeding to the unloading station 50. This permits the containers to cool sufficiently so that they may be handled and removed from the carrier plates 35 when they reach the unloading station 5% In starting the machine, a loaded carrier plate has to reach the point in the central zone where a row of containers is in position to receive the coating material before the operation of the machine may be made entirely automatic. For this reason, provision is made to permit the conveyor to be advanced as the carrier plates are loaded by manual controls and provision is also made for fully automatic operation. In the manual operation of the machine, the. flux pump and the tin pump may be placed in operation at appro priate times as containers reach the fluxing position and the tinning positions, respectively.

A main circuit and a control circuit suitable for operating the machine which has just been described are illustrated schematically in Figs. 18 and 19 (in simplified form). In the main circuit, Fig. 18, a switch H5 connects power lines IIB, Hi and H8 to a source of electrical energy S, in this case a three phase system, that is suitable for operating the various working parts of the machine such as motors and heaters. The control circuit, Fig. 19, controls the operation of the working parts in proper timed relation to the operation of the machine.

In the main circuit, Fig. 18, the conveyor motor 22, the work rotating motor 81, the flux pump motor 96 and the tin pump motor 99 are respec- 8. tively connected to the power lines H6, Ill and H8 through suitable protective devices such as overload relays, indicated at OLC, OLR, OLF and GUI, and these relays may also be interconnected so that when the contacts of any one of the overload relays open, the contacts of the other relays will also open and the operation of all of the motors will be stopped.

The conveyor motor 22 is connected to drive the conveyor forward when relay controlled con tactors LCF are closed and in reverse when relay controlled contactors LCR are closed. The work rotating motor ill, the flux pump motor and the tin pump motor 99 are respectively connected to the power lines H 5, l I! and Us by relay controlled contactors LR, LF and LT. The heaters 59 and 65 in the preheat zone, the heaters 6! in the two positions of the heat treating zone, the heaters I86 in the tin tank and the heaters 5&5 in the flux tank are respectively connected to the power lines by relay controlled contactors P, EHT and 21-1'1, TT and FT. The tin line heaters H3 and ltd and the tin tray and tin manifold and stand pipe heaters E8 and '59 are respectively connected to the power lines I l 5 and I it through thermostatically controlled switches H9, I26 and HI.

In the control circuit, Fig. 19, a manually operable switch 122 connects the control power lines I23 and I24 to a source of electrical energy S that is suitable for operating the various control relays. A power line I23a (to which a number of the controls are connected) is connected to the power line E23 through normally open, thermostatically controlled, relay operated contacts PTR, il-ITR, 2HTR, TTR, FIR and normally closed relays controlled contacts OLC', OLR, FOL and TOL. The relays controlling the contacts PTR, IHTR, ZHTR, TTR and FTR are oper ated by thermostats located in the preheat zone, in the heat treating zone (2 positions), the tin tank and the flux tank, respectively, to close these contacts when the required temperatures in the heating zones and in the flux and tin tanks have been reached. Thus, the machin cannot operate until all of these contacts have been closed. The contacts COL, ROL, FOL and TOL' are normally closed and are opened when any one of the overload relays in the main circuit opens.

A manually operable safety switch I25 is also connected in the line I230; and is located at a position on the machine where it can be conveniently reached by the operator of the machine so that the operator can stop all further operation of the machine by opening this switch.

The controls for the conveyor motor are connected to the power lines I23a and I24 through lines I25 and I2? (horizontal) and manually operable momentary push button switches I28 and IN. When the push button switches I28 and I29 are in the position shown, the line I26 connects the relay LCR to the power lines l23a and I24 when the push button switch I29 is depressed and causes the conveyor to be driven in reverse.

When the push button I28 is depressed momentarily, a conveyor motor relay LCF is connected by the line 621 to the power lines [23a and I24 and closes the contactors LCF for operating the conveyor in a forward direction. The line I2! includes a pair of photo-electric relay contacts IPR. and ZPR, a limit switch I30 and a conveyor stop switch I3l. Line I34 parallels the circuit of line I27, through the switch I28 and the contacts IPR and ZPR. Line I34 includes a push button switch I34, normally open contacts LCF and normally open contacts IPLS of a conveyor position limit switch I35 (see Fig. l). The contacts LCF are closed by the relay LCF when push button I28 is momentarily depressed and the conveyor continues to run forward until it trips th position limit switch I35 and opens its contacts iPL-S which occurs when the conveyor has advanced one step.

The conveyor may be inched forward or in reverse by depressing the push button switches I35 or I25, respectively. When the push button switch I 34 is depressed, it by-passes switch I28 through line I36 momentarily. The photo-electric relays controlling the contacts IPR and ZPR are operated by photo-electric cells (not shown) located at the loading and unloading stations 49 and c of the machine, respectively. The photo-electric cell, operating the relay that controls the contacts IPR, is located at the loading station and is arranged so that a flag 32 located above each container at the loading station (see Figs. 3 and 4 must be raised by a container being placed on the carrier plate at the appropriate position to mov the flag out of a beam of light that is focused on the photo-electric cell. When a container has been placed at each position on the carrier-plate at the loading station, all of the flags I32 are raised and the beam of light strikes the photo-electric cell causing the contacts I PR to be closed.

The photo-electriqcell, operating the relay that controls the contacts 21 3, is located at the unloading station and a beam oflight focused on it is blocked by any container remaining at any position on the carrier plate at that station and the contacts ZPR are held open. When all of the containers have been removed from the carrier plate at the unloading station, the photo-electric relay controlling the contacts zPR operates to close these contacts.

In this manner, the photo-electric relays through their contacts IPR and ZPR permit the conveyor motor to be operated to move the con-' veyor forward only after a container has been put in place at every position of the carrier plate at the loading station and all of the containers have been removed from the carrier plate at the unloading station. Also, the arrival of a'loaded carrier plate at the loading station and an empty carrier plate at the loading station automatically causes the conveyor motor to be stopped after the conveyor limit switch contacts IPLS have been opened.

The control circuits for the upper and lower the switch I3? through timer controlled relay contacts TCRI and an elevator valve opening relay EVE to the power line I24.

Connected in parallel with the line 158a through either contacts EULS of an upper limit switch i ifi that operated by the lower elevator (see Fig. l) or normally open contacts TRI of a cycle timing relay are lines l4I,-I42,' I43 and I44. v Th line i li is connected to the power line 524 through a cycle timing relay The normally closed time-delayed opening contacts, T0 of the cycle timing relay and; a timer motor {I'M are connected across the timing relay TR by the line TOR to the power lines through the time delayed closing contacts TL that are closed by the operation of the cycle timing relay TR. The line I43 connects the work rotating relay LE to the power lines through a manually operable switch I45 and contactors LT" that are controlled by the tin pump relay LT.

The tin pump relay LTR, which controls the tin pump motor contactors LT, is connected to the power lines by line I44 throughthe tin pump limit switch IIEi (TLS), a manually operable switch Hi5, and normally closed contacts TR3 of the cycle timingrelay TR'. The tin pump water valve solenoid TWV is also connected through the tin pump limitswitch I It (TLS) to the power line I24 and to the power line I23 by line I41 so that this valve is, opened as soon as the tin pump is lowered into the tin tank.

The flux pump relay LFR which controls the flux pump motor contactors LP is connected to the power lines by the line I48 through normally closed cycle timer relay contacts TR3, a manually operable switch 49 and the flux pump limit switch IE9 (FLS). The flux pump water valve solenoid FWV is connected to the power line I24 through the flux pump limit switch I09 and to the power line 23 by line I59.

An elevator control relay ECR. is connected to the power lines are and I23a by the line I5I through either the normally open elevator control relay contacts ECRI or by depressing the push'button switch it lj A valve operating solenoid AVUS that is operated to shift the elevator control valve for the elevator operating cylinders when the elevator reaches its up position, is connected to the power lines E24 and I'Zfia by line vI52 in which normally open contacts EVRI that the closed by the elevator relay EVR and normally open contacts ECRZ that are closed by the elevator control relay EJR are located. A second valve operating solenoid AVDS that is operated to shiftthe elevator cylinder control valve when the elevator reaches its down position, is

connected to the power lines I24 and I23a by line I53 through normally closed elevator relay ering the flux and tinv pumps into their respective tanks. When the pumps are in this position,

they close the limit switches I68 and M0 in the control circuits which turn on the cooling water to the-pumps and the cooling water remains on at all times while the pumps are in their respective tanks. The limit switches also close the control circuits to the pump motors so that theymay be operated at appropriate times.

The operator then loads thecarrier plate at the loading station by placing a container in inverted position on each of the rotatable sleeves. When the last container is placed on the carrier plate, it clears the photmelectric relay which'opcrates to close the contacts EPR. The operator then closes the conveyor start switch I28 and the conveyor moves one position bringing the loadedcarrier' plate into the preheat zone and the next carrier plate to the loading station. vThis operation is repeated and the first carrier plate advances to the fiuxing position.

11 In order to flux but not tin when the elevator is raised, the elevator control switch l3! and the switch M9 controlling the flux pump relay is closed. This causes the elevator to be raised and the timer and flux pump go through their required cycle upon completion of which the elevator returns to its down position, but the conveyor does not move. During this period, the

'third carrier plate has been loaded and the conveyor may then be advanced at the proper time by closing the manual switch I28 to bring the first loaded carrier plate to the tinning position.

The fourth carrier plate is now loaded and the switches M and M5 in the work rotating motor and tin pump motor control circuits are closed. This places the machine in condition for full automatic operation. The machine may then be operated by automatic controls and may continue to operate on an automatic cycle until stopped by the operator or a failure such as would cause the opening of an overload relay.

hen the switches I37, M5, M6 and use have been closed, the machine may be automatically operated. Under these conditions, the normally closed contacts of the position limit switch I are opened by the conveyor after it has moved one position. This stops the conveyor and the valves controlling the operation of the elevator pistons $5 and 85 are then operated to cause the lower elevator 63 to rise and the upper elevator fi lto descend. When the lower elevator $3 has risen to its top station, it closes the normally open contacts of the upper limit switch Mi) which causes the flux and tin pumps 98 and as and the work rotating motor 81 to operate. The operation of these units is under the control of a timer. When the timer times out, the operation of the flux and tin pumps and the Work rotating motor ceases and the valves for the elevator operating pistons are shifted causing the upper elevator to rise and permitting the lower elevator to descend.

When the lower elevator reaches its lower position, it closes the normally open contacts of the lower limit switch I39 and places the conveyor in condition to be advanced one position when all of the containers have been placed on it at the loading station and have been removed from it at the unloading station. The conveyor may then be advanced one position by closing the push button switch I28. For fully automatic operation, a timing relay that is placed in operation at an appropriate time, may be provided to close contacts in parallel with the contacts of the push button switch 28 for operating the conveyor motor at the proper time. When the conveyor moves forward to its next position, the cycle of operations is automatically repeated. During the time that the conveyor remains at one position, the containers in the preheating zone 56 and the heat treatment zone 58 are heated to the proper temperatures as required.

It will be understood that various changes and modifications may be made in the embodiment of the invention illustrated and described herein without departing from the scope of the invention as described by the following claims.

I claim:

1. A machine for applying a protective coating of material such as tin to the inside of a metal container such as a fire extinguisher shell which includes, a conveyor of the continuous type, said conveyor being movable step by step along a horizontal path to a plurality of work positions, rotatable members carried by said conveyor for supporting containers in inverted position at spaced intervals along said conveyor, each of said rotatable container supporting members having an opening extending therethrough and communicating with the interior of the container supported thereon, vertically reciprocable elevator, means carried by said elevator for simultaneously applying a flux to the inside of a container at one position on the conveyor and a coating of protective material to a container at the next position on the conveyor, said last-mentioned means including a pair of upwardly extending stand pipes spaced from each other, the first of said pipes having a spray head at its end being positioned beneath and in alignment with opening in the container supporting; member at the first of said positions of the conveyor and the second of said pipes being heated and having a nozzle at its end, said heated pipe being positioned beneath and in alignment with the open ing in the container supporting member at the second of said positions of the conveyor, said stand pipes extending through the openings in the respective container supporting members and into the interior of the containers supported thereon when the elevator is in its raised position and means for rotating the container at the sec- 0nd of said positions, said rotating means being located above the container at said second position and being vertically reciprocable into and out of rotating engagement with said container, a heating chamber through which the container passes in its movement by the conveyor, said heating chamber being located at a position in advance of the flux applying position of the conveyor, and a second chamber through which the container passes in the movement oi the conveyor, said second chamber being located at a position after the coating applying p sition of the conveyor.

2. A machine for applying a protective coating of material such as tin to the inside of a metal container such as a fire extinguisher shell which includes, a conveyor of the continuous type, said conveyor being movable step by step along a horizontal path to a plurality of work; positions, rotatable members carried by said conveyor for supporting containers in inverted position at spaced intervals along said conveyor, each of said rotatable container supporting members having an opening extending therethrough and communicating with the interior f the container supported thereon, vertically reciprocable elevator located beneath the horizontal path of the conveyor, means carried by the elevator means for simultaneously applying a flux to the inside of a container at one position on the conveyor and a coating of protective material to a container at the next position on the conveyor, said last-mentioned means including a pair of spaced, upwardly extending stand pipes having nozzles at their ends, the first of said pipes being positioned be neath and in alignment with the opening in the container supporting member at the first of said into and out of rotating engagement with said container, a heated tank containing a supply of a fiuxing material, means communicating with the first stand pipe and the flux tank for supplying fluxing material to said first pipe under pressure, a heated tank containing a supply of coating material in a fluid state and means communicating with the second stand pipe and the supply of coating material for supplying fluid coating material to said second pipe under pressure.

3. A machine for applying a protective coating of material such as tin to the inside of a metal container such as a lire extinguisher shell as defined in claim 2 which includes heaters for heating the second of said stand pipes and the means connecting said second pipe to the tin tank.

4. A machine for applying a protective coating of material such as tin to the inside of a metal container such as a fire extinguisher shell which includes, a conveyor of the continuous type, said conveyor being movable step by step along a horizontal path to a plurality of work positions, rotatable members carried by said conveyor for supporting containers in inverted position at spaced intervals along said conveyor, each of said rotatable container supporting members an opening extending therethrough and communicating with the interior of the container supported thereon, vertically reciprocable elevator located beneath the horizontal path of the conveyor, means carried by the conveyor for simultaneously applying a flux to the inside of a container at one position on the conveyor and a coating of protective material to a container at the next position on the conveyor, said last-mentioned means including a pair of spaced, upwardly extending stand pipes having nozzles at their ends, the first of said pipes being positioned beneath and in alignment with the opening in the container supporting member at the first of said positions of the conveyor and the second oi said pipes being positioned beneath and in alignment "ith the opening in the container supporting member at the second of said positions of the conveyor, sai stand pipes extending through the a heated tank containing a supply of coating ma- Y terial in a fluid state, heated means communicat ing with the second stand pipe and the supply of coating material for supplying fluidcoating material under pressure to said pipe and heating means for heating a coated container at a position of the conveyor following the coating position of the conveyor.

5. A machine for applying a protective coating f of material such as tints the inside of a metal container such as a fire extinguisher shell'as'de fined in claim 4 which includes heated means located beneath the container during said lastmentioned heating for'collecting coating material drained from' said container, said last-mentioned means having connections to the tin tank.

fiiln'anapparatus for ap-plyinga coating of protective material simultaneously to the interiors of a plurality of containers, the combination of means for rotatably supporting a row of containers in inverted position and in spaced relation to each other, intermittently operated conveyor means for moving successive rows of said containers sequentially to a plurality of positions in a step by step movement, heating means for preheating a row of the containers at one of said positions, means for applying flux to the interiors of a row of preheated containers at another of said positions, means for applying a coating of protective material to the interiors of a row of fiuxed containers at still another of said positions and independently motor driven means for rotating each container of the row at said last-mentioned position as the coating material is applied to the interior thereof.

'7. In an apparatus for applying a coating of protective material simultaneously to the interiors of a plurality of containers, the combination of means for rotatably supporting a row of containers in inverted position and in spaced relation to each other, intermittently operated conveyor means for moving successive rows of said containers sequentially to a plurality of positions in a step by step movement, means for preventing operation of the conveyor until a container is placed in inverted position on the rotatable supporting means at each position in a row at an initial position of the conveyor means, heating means for preheating one row of the containers at a position of the conveyor following said initial position, means for applying flux to the interiors of a row of preheated containers at subsequent positions of the conveyor, means for applying a coating of protective material to the interiors of a row of fiuxed containers at a position of the conveyor subsequent to said fiuxing position and independently motor driven means for rotating the containers of the row at said last-mentioned position as the coating material is applied to the interiors thereof.

8. In an apparatus for applying a coating of protective material to the interior of a metal conta-iner and heat-treating the container to relieve stresses in the metal thereof, the combination of means for rotatahly supporting a series of containers in inverted position and in spaced relation to each othenintermittently operated conveyor means for moving said inverted containers sequentially in step by step movement to a plurality of positions, heating means at a first of said positions for heating the container at said position, means at a second of said positions for applying a flux to the interior of the container at said second position, means a third of said positions for applying a coating of protective material to the interior of the container at saidthird position, independently motor driven means forrotating the container at said third position simultaneously with the applying of coating material thereto and heater means located at at least one position following said third position for heating the container at said last-mentioned position. l

9. hi an apparatus for applying a coating of protective materialtotheinterior of a metal container and heat-treating the container to relieve stresses in the metal thereof, tr e ccmbination oii 

19. THE METHOD OF APPLYING A PROTECTIVE COATING OF TIN TO THE INTERIOR OF A METAL CONTAINER COMPRISING THE STEPS OF ROTATABLY SUPPORTING A CONTAINER IN AN INVERTED POSITION AND THEN BODILY MOVING THE INVERTED CONTAINER IN STEP BY STEP MOVEMEMT TO A PLURALITY OF WORK POSITIONS, PREHEATING THE CONTAINER AT THE FIRST OF SAID WORK POSITONS, THEN APPLYING A FLUX TO THE INTERIOR OF THE CONTAINER AT A SUBSEQUENT WORK POSITION AND THEN SPRAYING MOLTEN TIN ON THE INTERIOR OF THE CONTAINER WHILE ROTATING THE CONTAINER AT A WORK POSITION IMMEDIATELY FOLLOWING THE APPLICATION OF THE FLUX THERETO, THE STEPS OF APPLYING OF THE FLUX AND SPRAYING OF THE TIN BEING CARRIED OUT WITH THE CONTAINER BEING MAINTAINED AT AN ELEVATED TEMPERATURE. 